1. Field of the Invention
The present invention relates to a seat recliner for a vehicle, in particular, a seat recliner for a vehicle which is capable of being tightly engaged with gears without any moving space at the time of adjusting the rotation angle of the seatback for a vehicle.
2. Description of the Related Art
In general, a seat recliner for a vehicle is employed for adjusting the rotation angle of the seatback installed in a vehicle.
Seats are installed in a vehicle for a driver and fellow passengers to sit on, and especially seats for the driver and the assistant driver can be moved forwardly and rearwardly by means of transporting rails installed in the bottom surface of the vehicle body. Accordingly, when the seats for the driver and the assistant driver are fabricated, the seatback and the seat cushion are separately fabricated, and the angle of the seatback can be freely adjusted by means of the actuation of the seat recliner located between them, so that the driver and the assistant driver can take their seats comfortably and safely by adjusting positions of the seats and the angles of the seatbacks properly depending on their body shapes.
There have been several types of conventional seat recliner for a vehicle.
One of them is the seat recliner for the vehicle disclosed in Korean Utility Model Registration No. 313604.
In the conventional seat recliner for vehicle as explained above, an actuating cam pushes out a lock gear supported by a lock gear supporting portion of a holder outwardly on condition that it is located at the outer peripheral side by means of restoring force of a return spring, respective end of which being fixed to the actuating cam and the holder at the state of wound around the rotation shaft, so that the outside gear teeth formed at the outside side of the lock gear supporting portion can be engaged with an inside gear teeth formed at the inner peripheral edge of a sector gear to thereby stop rotation of the sector gear fixed to the seatback. As a result, the seatback can be maintained at desired angles. Then, the angles of the seatback can be freely adjusted through the rotation of the sector gear fixed to the seatback in accordance with the separation between the outside gear teeth and the inside gear teeth, as the lock gear is pushed inwardly based on the rotation angle of the actuating cam urging the lock gear by the rotation of the rotation shaft, when a lever connected to the rotation shaft is held and pulled. Further, when the outside force applied to the lever is relieved after the completion of the angle adjustment of the seatback, the actuating cam pushes again the lock gear to the outside by means of the storing force of the return spring to thereby make the outside gear teeth and the inside gear teeth engaged with each other to result in maintenance of the fixed state of the seatback.
Such conventional seat recliner for the vehicle has been constructed and operated as follows. The lock gear is configured to move along transporting support surfaces of the seat recliner with regard to its center point after the lock gear to be located to contact with the first, second and the third transporting surfaces of the seat recliner having an arc shape. Further, the lock gear is provided with a relief projection and an engaging projection at respective inside end thereof and is moved by means of an actuating projection of the actuating cam, and the outside gear teeth of the lock gear are maintained to be tightly engaged with the inside gear teeth of the sector gear by making the locking projection to be closely contacted with the actuating projection of the actuating cam.
When artificial force is not applied to the rotation shaft at a state of fixing the seatback, the actuating projection of the actuating cam pushes the inner peripheral surface of the lock gear to the outside by means of the restoring force of the return spring so as to move the lock gear to the outside direction with regard to the first transporting support surface to thereby make the outside gear teeth to be engaged with the inside gear teeth of the sector gear, and then when the outside gear teeth of the lock gear is engaged with the inside gear teeth of the sector gear, as the actuating projection is maintained to be closely contacted with the locking projection to make the lock gear to be engaged with the sector gear tightly.
Further, when the angle of the seatback is required to be adjusted, the actuating projection which presses the locking projection according to the rotation angle of the actuating cam as the actuating cam rotates to one direction, pushes the relief projection to the rotation direction, so that the lock gear can move along the first transporting support surface with regard to the center point to thereby separate the outside gear teeth from the inside gear teeth to result in proper adjustment of the angle of the seatback due to free rotation of the sector gear.
However, in the conventional locking state of the seat recliner for the vehicle, the inside gear teeth and the outside gear teeth are at the state of engagement after the lock gear is moved to the outside direction along the first transporting support surface with regard to the center point. In this state, the fixing projection and the actuating projection of the actuating cam are maintained to simultaneously push the inside surface of the lock gear and the locking gear to thereby engage tightly with the outside gear teeth portion and the inside gear teeth portion which are joining vertical portion of the center point of the actuating cam and the other center point. As explained above, in the locking state, the outside gear teeth portion and the inside gear teeth portion are caught by three lock gears arranged at identical degrees of 120.
In this instance, it is intended that the strength of the gear teeth can be improved by allowing the lock gear to be applied of the outside force vertically and distributing force to all the outside gear teeth of the lock gear while locating a rotation center of the lock gear, which is actuated by the actuating cam, to be on a center line on which the outside and inside gear teeth are engaged with each other, that is, which is perpendicular to the center line of the lock gear. However, because the supporting point of the actuating cam and the lock gear which are defined to produce the strength of the outside and inside gear teeth, which becomes the criteria for the stress of the cut-away portion of the gear teeth produced from the outside force, has been configured to be strayed off and to be located away from the center line of the lock gear, and the force produced from the outside force can not be distributed and transferred effectively to the driving center of the lock gear which is vertical to the center line of the lock gear, so that it is impossible to maximize the supporting force of the actuating cam with regard to the lock gear produced from the outside force to thereby distribute the force to the outside gear teeth in imbalance to result in reduction of the strength.
Furthermore, although the stress has been made to concentrate due to the outside force and the strength of the lock gear has been improved by making the actuating projection of the cam and the locking projection press the lock gear and the actuating cam respectively, such two point supporting force can only compensate for the strength with regard to the front load, that is, it can operate in a side direction with regard to the relief pressure of the gear teeth cut away portion, which is produced from the deformation of the holder supporting the lock gear and is concentrated on the gear teeth cut away portion along the load direction, and it can not compensate for the back load, so that the strength deviation of the seat recliner between the forward and backward direction becomes larger to thereby cause several defects in the products such as deterioration of the quality of the products, and the like in actual producing conditions.
In addition, the lock gear has the rotation shaft at place vertical to the center line of the gear teeth by means of the actuating cam, and it is driven along the inside supporting surface of the holder defining two arcs from the rotation center of the lock gear, so that moving interval can be adjusted and structure increasing the strength of the outside and inside gear teeth can be defined by making both sides of the lock gear contact in face to face relation. However, as the driving surface of the lock gear restraints both sides of the lock gear on the condition of contacting in face to face relation, space is formed between the lock gear and the holder supporting it to provide smooth operation and management of the moving interval to thereby result in formation of the moving interval during the operation.